Air force waiting on hi-tech spy planes

Australia's first two Wedgetail surveillance aircraft remain on target for delivery by the end of November, but full capability of the advanced radar could still be two years away.

The aircraft was now ready to be used for training and initial operations, director of the Wedgetail project Air Vice Marshal Chris Deeble said.

"But there are some aspects of the radar that we are going to have to further develop," he told reporters in Seattle.

"There is more work that we are going to have to do which may take a up to a couple of years beyond where we are to get to that final stage."

Under the $3 billion Wedgetail program, Australia is buying six Boeing 737 aircraft equipped with the advanced MESA radar, able to watch over a vast area of sky and direct fighters to intercept intruders.

The aircraft were slated for introduction to service in 2006 but technical problems with the radar have resulted in major delays, leading to speculation within defence the project might need to be cancelled.

There now have been significant advances.

A study conducted by US radar expert Lincoln Laboratories concluded the radar architecture was fundamentally sound.

And real-life trials conducted over the Northern Territory concluded the radar worked effectively at controlling fighter interception of intruders, subject to some reservations.

The key remaining radar problems relate to its clutter performance - the ability to detect targets such as low-flying aircraft against a ground or water backdrop in certain circumstances - sidelobes - extraneous radar signals which could create false images - and stability, where some combinations of operator commands cause mission computers to halt temporarily or even lock up.

Two aircraft, with limited capability, will be delivered to the RAAF on November 30, with four others - in full configuration - delivered between March and September 2010.

The first two aircraft will then be upgraded to full specification.

Boeing says it is proud to have its name on the Wedgetail, describing it as a highly-advanced capability.